Method of collapsing an implantable appliance

ABSTRACT

This is a method of collapsing an artificial blood vessel A. The artificial blood vessel A comprises a pair of discrete end wire rings 10 1 , 10 2 , a tubular cover 7 made of a sheet of flexible, tensile material which connects the end wire rings 10 1 , 10 2 , and a plurality of intermediate wire rings 12 arranged spaced apart between the end wire rings 10 1 , 10 2  and circumferentially fixed to the cover 7 by suturing or with adhesive. 
     A plurality of dividing points 41 1 , 43 1  which bisect the circumference of the front end wire ring 10 1  are pulled forward while the movement of the midpoints 42 1 , 44 1  between the dividing points 41 1 , 43 1  following the movement of the dividing points 41 1 , 43 1  are restrained by the projections 18c on a tapered surface 18d of a funnelled tube 18 so as to fold the front end wire ring 10 1  into a wavy shape, with the dividing points 43 1 , 43 1  forming forwardly directed peaks and the midpoints 42 1 , 44 1  forming the bottoms of forwardly directed valleys, and the dividing points of the front wire ring are pulled farther forward so as to fold the intermediate wire rings 12 and the rear end wire ring 10 2  into a regular wavy shape having the same phase as that of the front wire ring 10 1  by the effect of restraint by the tapered surface 18d and the projections 18c, thereby to collapse the artificial blood vessel A as a whole into a small size.

This application is a divisional of application Ser. No. 08/411,670,filed Apr. 12, 1995 now abandoned.

FIELD OF THE ART

This invention relates to appliances for medical treatment and, moreparticularly, to an appliance collapsible for insertion into a humanorgan and capable of resilient restoration (which will be referred to as"the appliance to be implanted" in this specification and claims), to amethod of collapsing the appliance to be implanted, and to a device forintroducing the collapsed appliance to be implanted into a catheter.

PRIOR ART

The artificial blood vessel is an example of the appliance to heimplanted. At present, treatment of, for example, aortic aneurysm isconducted by implanting an artificial blood vessel. In particular, theportion of a blood vessel which has an aneurysm is removed by resection,and an artificial blood vessel is implanted in place of the resectedportion and connected to the remaining blood vessel by suturing or thelike.

The above-mentioned method of surgically implanting artificial bloodvessels for treatment of aortic aneurysm, however, is highly dangerous.Especially, an emergency operation for treatment of a ruptured aneurysmhas a low life-saying rate, and an operation of dissecting aorticaneurysm is difficult to conduct and has a high death rate.

Therefore, in order to treat these diseases without a surgicaloperation, a method has been developed of introducing into a catheter anappliance such as an artificial blood vessel in collapsed condition intoa human organ such as a blood vessel, and transporting the appliance toa desired position such as an affected or constricted portion thereof,where the appliance is released so as to be expanded and implanted therewith accuracy.

The appliance to be implanted comprises a pair of end wire rings and aframe mainly composed of connecting wires which connect theabove-mentioned end wire rings. The appliance is pushed at the rear endwire ring into a catheter and transported to a desired organ in a humanbody. In order to transport the appliance, the force applied to the rearend wire ring should be transmitted to the front end wire ring.Therefore, it is indispensable that the frame should be made ofcomparatively strong metal and that the appliance should have the frameas an inevitable constructing element. If the above-mentioned frame isused, interference is likely to take place between the end wire ringsand the frame and prevents the end wire ring from being folded, whichmakes it difficult to fold the end wire rings into a regular wavy shape.The difficulty in folding the end wire rings will make it difficult tocollapse the whole appliance to be implanted into a small size.

As the end wire rings have an elastic limit, if a force exceeding theelastic limit is applied to the rings, the end wire rings folded forinsertion into a catheter suffer plastic deformation so that the endwire rings may not be restored to a proper shape when released at anobjective position in a human organ. The distortions caused by theplastic deformation may give rise to sliding resistance and prevent theappliance to be implanted from traveling in a catheter, thereby to makeit difficult or impossible for the appliance to be transported to adesired position.

In addition, a frame, if used in the appliance to be implanted, islikely to hinder the appliance from being implanted in an appropriateshape into a human organ. Especially, in placing the appliance into abent portion of a human organ, the frame may be deformed into a flatshape because different parts of the frame interfere with each other.Even if the appliance has been implanted, it may not be able to functionas it is intended to. In the conventional frame, the wire of the wirerings provided at the opposite ends of the frame is exposed, so that theinner wall of a human organ may be scratched and damaged by the wire andblood is likely to leak out from the end wire rings because the ringsare not adhered closely to the inner wall of the human organ.

Even though a check valve is provided at the outer end of a catheterwhose front end has been inserted into the blood vessel of a human bodybeforehand, the check valve must be temporarily opened when thecollapsed appliance is introduced into the catheter, thereby to cause alot of bleeding. It is therefor desirable to provide means forpreventing bleeding.

The present invention has been accomplished to solve the above-mentionedproblems. The object of the invention is to develop an appliance ofnon-frame type, which can solve all of the above-mentioned problems.

DISCLOSURE OF THE INVENTION

The method of collapsing the appliance to be implanted in accordancewith the invention is characterized by that the appliance to beimplanted comprises a pair of discrete end wire rings, a tubular covermade of a sheet of flexible, tensile material which connects theabove-mentioned end wire rings, and a plurality of intermediate wirerings arranged spaced apart between the above-mentioned end wire ringsand circumferentially fixed to the above-mentioned cover by suturing orwith adhesive; and that the method comprises the steps of; pullingforward the front end wire ring at a plurality of dividing points whichequally divide the circumference of the front end wire ring whilerestraining the midpoints between each adjacent two dividing points by atapered surface from moving forward following the forward movement ofthe dividing points, thereby to fold the front end wire ring into a wavyshape with the dividing points forming forwardly directed peaks and themidpoints forming the bottoms of forwardly directed valleys, and pullingthe dividing points of the front wire ring farther forward thereby tofold the intermediate wire rings and the rear end wire ring into a wavyshape having the same phase as that of the front end wire ring by theeffect of restraint with the tapered surface.

A loop for a pull string to be passed through may be formed at each ofthe dividing points on the front end wire ring so that a front pullstring may be passed through each of the loops and pulled forward. Inparticular, a common pull string may advantageously be passed through aplurality of loops so that the dividing points may be gathered togetherby pulling the common front pull string. A funnelled guide tube whosebore diameter is gradually reduced toward its forward end may be used togather the dividing points and the midpoints by pulling forward thedividing points on the front end wire ring of the appliance to beimplanted inserted into the funnelled guide tube through its rearopening. In particular, resiliently deformable projections can be formedon the tapered inner surface of the funnelled guide tube so as to bringthe midpoints into contact with the projections thereby to effectivelyrestrain the midpoints from moving forward following the movement of thedividing points and cause the midpoints to approach to each other. Theend wire rings can be circumferentially covered with elastic protectivematerial.

The appliance to be implanted in accordance with the invention ischaracterized by that a pair of discrete end wire rings which areresiliently foldable are provided at opposite ends; that the end Wirerings are connected by only a tubular cover made of a sheet of flexible,tensile material; and that a plurality of intermediate wire rings arearranged between the above-mentioned end wire rings and fixed to theabove-mentioned cover at appropriate points on the circumference thereofby suturing or with adhesive.

The flexible, tensile sheet may be made, for example, of warps extendingin the axial direction of the appliance to be implanted woven with weftsextending in the circumferential direction thereof. The warps are madeof mono-filament of polyester capable of keeping its shape and the weftsare made of multi-filament of polyester having waterproofness.

The tubular cover may be in the form of bellows. Especially, the endwire rings may advantageously be connected by restraining strings-so asto prevent the bellows from overstretching to exceed a given limit. Theend wire rings can be circumferentially covered with an elasticprotective material. Further, thorns can be provided on thecircumference of at least one of the wire rings so as to stick into ahuman organ to be embedded therein. The thorns may be effectively formedby curving a wire into a loop, crossing the opposite end portions of thewire, and fixing the crossing point, thereby to form the opposite endportions into the thorns.

The device for introducing the appliance to be implanted in collapsedstate into a catheter in accordance with the invention comprises anattachment having a flexible check valve which closes an open endthereof and fixed to an open end of a catheter, and a cartridgeremovably attachable to the above-mentioned attachment and having anopen end closed by a flexible check valve and a front end portionconnected to the above-mentioned catheter when the cartridge is attachedto the attachment; and by that the check valve of the cartridge ispushed open to introduce the appliance to be implanted into thecartridge, and while the check valve of the cartridge is kept nearlyclosed, the front end portion of the cartridge is inserted into thecatheter by pushing the check valve of the attachment open.

The bore diameter of the attachment of the catheter is made larger thanthat of the open end of the catheter, so that when the cartridge isattached, the bore of the front end portion of the cartridge may besmoothly connected to the open end of the catheter through theattachment of the catheter.

With the method of collapsing the appliance to be implanted inaccordance with the invention, the operation of collapsing the appliancecan be conducted with ease and accuracy. It is difficult to fold thefront end wire ring into such a small size that can be contained in acatheter just by applying non-directional external force thereto.However, if the dividing points which equally divide the circumferenceof the front end wire ring are pulled forward with the midpointsprovided between the dividing points being restrained by a taperedsurface from moving forward following the dividing points, the front endwire ring is folded into a wavy shape with the midpoints serving asfootholds and with the dividing points forming forwardly directed peaksand the midpoints forming the bottoms of forwardly directed valleys.After the front end wire ring has been bent, the intermediate and therear end wire rings also are folded into a wavy shape having the samephase as that of the front end wire ring by pulling farther forward thedividing points on the front end wire ring to transmit the pulling forceto the intermediate and the rear end wire rings through the tensilecover, and by simultaneously restraining the intermediate and the rearend wire rings by means of a tapered surface, thereby to collapse thewhole appliance into a small size with ease.

What should especially be referred to is that the method of collapsingthe appliance to be implanted in accordance with the invention ischaracterized by that a pair of end wire rings provided at the oppositeends of the appliance are connected by only a tubular cover which ismade of a sheet of flexible, tensile material; and that the front endwire ring is pulled forward. The conventional method, in which the rearend portion of the appliance to be implanted is pushed to insert theappliance into a human organ, requires a relatively strong frame mademainly of connecting wire rings in order to transmit the force appliedto the rear end of the appliance to the forward portion thereof.However, the invention is based on pulling the front end wire ringforward, thereby to make it possible to insert the appliance with easeeven without a frame. In addition, the cover follows the movement of thewire rings being folded and is transformed into any desired shape,thereby to avoid interference between the wire rings and the frame.Consequently, by the method of collapsing the appliance in accordancewith this invention it is possible to fold each of the wire rings into awavy shape and to collapse the whole appliance into a small size withease.

The operation of folding the wire rings is conducted with ease byforming loops for a pull string to be passed through at the dividingpoints on the front end wire ring and pulling forward a front pullstring passed through the loops. In particular, a common front pullstring passed through a plurality of loops is more effective to changethe pulling force to a force to fold the wire rings because the dividingpoints are gathered toward each other.

In collapsing the appliance, a funnelled guide tube whose bore diameteris-gradually reduced in the forward direction may advantageously beused, so that the dividing points and midpoints of the wire rings aregathered toward each other as the appliance to be implanted is insertedfarther into the funnelled tube, thereby to collapse the appliance as awhole into a small size. If projections resiliently deformable andengageable with the midpoints are formed on the tapered inner surface ofthe funnelled guide tube, the midpoints are urged toward each other bythe counterforce from the projections, and a space is formed between theend wire rings and the funnelled guide tube, thereby effectively toprevent the appliance and the funnelled guide tube from closelycontacting each other to increase sliding resistance therebetween sothat the appliance cannot be moved in the guide tube.

Elastic protective material circumferentially covering the end wirerings is useful to prevent the appliance from being damaged whencollapsed into a small size. If the wire ring is bent to such a degreethat the elastic limit is exceeded, not only it becomes difficult forthe ring to be restored to its original annular shape but also itbecomes impossible to move the ring in a catheter due to the bentportion being caught in the catheter. However, if protective material isprovided, the material disperses the tension which would otherwise beexerted locally on the dividing points when the points are stronglypulled, thereby to prevent tension from being applied locally to thedividing points so that the elastic limit is exceeded to bent the wirering. The protective material prevents the front end wire ring frombeing plastically deformed, and provides it with a proper capability ofresilient restoration to an annular shape and of traveling smoothly in acatheter, thereby to fold the front end wire ring into a regular wavyform.

The appliance having no frame, as mentioned above, properly functions asan artificial blood vessel. The appliance in accordance with theinvention has a feature that the cover itself is tensile and is held bythe wire rings at both ends and the intermediate wire rings atappropriate points thereof. Therefore, when the whole appliance isreleased from the state of being collapsed and each of the wire ringsare resiliently restored to the annular shape, the cover is resilientlyrestored to its original proper tubular shape. The conventionalappliance having a frame is likely to be deformed flatly because ofmutual interference of the component parts when it is arranged in a bentportion of a human organ. However, the appliance of the invention havingno frame can be transformed into any desired shape so as to conform todifferent shapes of a human organ.

A sheet woven with warps and wefts, in which the warps are made ofmono-filament of polyester and the wefts are of multi-filament ofpolyester, makes the whole appliance flexible. In addition, the warpsprovide the cover of the appliance with tensile strength in the axialdirection and a capability of keeping its shape, and the wefts make thesheet closely woven and increase its waterproofness.

If the sheet of the cover is in the form of bellows, the whole applianceis bent smoothly, thereby to improve the condition of the appliance whenimplanted into a human organ. If the sheet of the cover is in the formof bellows, restraining strings connecting the front and the rear endwire rings can prevent the bellows from stretching to such a degree thatthe elastic limit is exceeded to be flat.

The elastic protective material circumferentially covering the wirerings can prevent, as mentioned previously, not only the wire rings frombeing plastically deformed when folded into a small size but also theinner wall of a human organ from being damaged by direct contact withthe wire rings. The protective material also acts as a seal to attachboth ends of the appliance to be implanted tightly to the inner wall ofa human body, thereby to effectively prevent leakage of blood throughthe ends of the appliance when implanted.

When thorns are provided projecting from the wire rings, they stick intothe inner wall of a human organ to be embedded therein so that the wholeappliance is fixed to the human organ. Therefore, the thorns effectivelyprevent the appliance from being displaced or even carried by blood flowdownstream in a blood vessel. The thorns are formed with ease by curvinga wire into a loop, crossing both end portions of the wire, andfixing.the crossed parts with a string or the like, even though thematerial of the wire is difficult to weld. The thorns thus formedreliably function as mentioned above for a long time.

In addition, with the device for introducing a collapsed appliance to beimplanted into a catheter in accordance with the invention it ispossible to introduce the appliance to be implanted smoothly into acatheter. In particular, the appliance to be implanted is inserted intothe cartridge by pushing the check valve open as far as the appliancereaches a position at which it is almost completely contained in thecartridge. Before or after the insertion, the cartridge is attached tothe attachment provided at the open end of the catheter, and then theappliance is pulled farther forward in that condition so as to beintroduced into the catheter through the attachment. When the checkvalve in the attachment is opened, the check valve of the cartridge isclosed, so that blood flowing into the cartridge is prevented fromflowing outside the body through the cartridge without fail. Inaddition, if the appliance is to be inserted directly into the catheter,the appliance cannot be inserted smoothly because of the catheter andthe appliance being flexible, and the catheter is bent by the forceapplied to the appliance, thereby to block the passage through which theappliance is to be inserted or to make the catheter fragile. On theother hand, if the appliance is to be inserted into the catheter throughthe attachment and the cartridge, by making the attachment and thecartridge strong and of such a shape as to be handled with ease itis-possible to solve the problem of the catheter being bent or otherwisedeformed, thereby to enable the appliance to be introduced into thecatheter smoothly and with ease. If the bore diameter of the attachmentis made bigger than that of the catheter and the bore diameter of thefront end of the cartridge is smoothly connected to that of the open endof the catheter when the cartridge is attached to the catheter, it ispossible to prevent the appliance to be implanted from being temporarilyswollen in the attachment and caught therein, and to introduce theappliance to be implanted deep into the catheter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an artificial blood vessel used in oneembodiment of the invention.

FIG. 2 is a vertical cross-sectional view of part of the artificialblood vessel.

FIG. 3 is a perspective view of a device for transporting the artificialblood vessel, used in the embodiment.

FIG. 4 is a perspective view of a device for introducing the artificialblood vessel, used in the embodiment.

FIG. 5 is an enlarged vertical cross-sectional view of part of theattachment shown in FIG. 4.

FIG. 6 is an enlarged vertical cross-sectional view of part of thecartridge shown in FIG. 4.

FIG. 7 is a perspective view of the artificial blood vessel throughwhich the device for transporting the artificial blood vessel is looselyinserted.

FIG. 8 is a perspective view showing a step to hold the artificial bloodvessel by means ok the device for transporting the artificial bloodvessel.

FIG. 9 is a perspective view showing a step to hold the artificial bloodvessel by means of the device for transporting the artificial bloodvessel.

FIG. 10 is an enlarged perspective view showing part of the artificialblood vessel kept by the device for transporting the artificial bloodvessel.

FIG. 11 is a perspective view showing a step to introduce the artificialblood vessel into a catheter.

FIG. 12 is a perspective view showing a step to introduce the artificialblood vessel into the catheter.

FIG. 13 is a perspective view showing a step to introduce the artificialblood vessel into the catheter by means of the device for introducingthe artificial blood vessel.

FIG. 14 shows the front end wire ring of the artificial blood vesselbeing folded.

FIG. 15 shows the front end wire ring of the artificial blood vesselbeing folded.

FIG. 16 shows the front end wire ring of the artificial blood vesselbeing folded.

FIG. 17 shows the front end wire ring of the artificial blood vesselbeing folded in a funnelled tube.

FIG. 18 shows the intermediate wire rings and the rear end wire rings ofthe artificial blood vessel being folded.

FIG. 19 shows the collapsed artificial blood vessel.

FIG. 20 shows the artificial blood vessel being inserted into thecartridge.

FIG. 21 shows the artificial blood vessel inserted into the cartridge.

FIG. 22 shows the artificial blood vessel transported from the cartridgeto the attachment.

FIG. 23 is a cross-sectional view showing the artificial blood vesseltransported to the affected portion.

FIG. 24 shows a step to release the artificial blood vessel at anaffected part in a blood vessel.

FIG. 25 shows a step to release the artificial blood vessel at theaffected part in the blood vessel.

FIG. 26 is a cross-sectional view showing the artificial blood vesselreleased at the affected portion in the blood vessel.

FIG. 27 shows a step to expand the artificial blood vessel by means of aballoon catheter.

FIG. 28 shows the principle of another embodiment of the invention.

FIG. 29 shows the principle of a different embodiment of the invention.

FIG. 30 is a perspective view corresponding to FIG. 12 of a furtherdifferent embodiment of the invention.

FIG. 31 is an enlarged perspective view of part of the above embodiment.

FIG. 32 is an enlarged cross-sectional view along the line Z--Z in FIG.31.

FIG. 33 is a perspective view corresponding to FIG. 31 of a modifiedform of the embodiment.

BEST MODES OF EMBODYING THE INVENTION

The invention will be described in detail with reference to theembodiments thereof shown in the accompanying drawings.

The artificial blood vessel A as the appliance to be implanted, which iscollapsed by the method in accordance with this invention, comprises, asshown in FIG. 1, a cover 7, end wire rings 10₁, 10₂ and intermediatewire rings 12.

The cover 7, as shown in FIG. 2, consists of a flexible, tensile sheetshaped into a tube of bellows, the diameter of which generallycorresponds to the normal diameter of that portion of the human bloodvessel at which the artificial blood vessel A is to be implanted. Thesheet of the cover 7 is, for example, of warps extending in the axialdirection of the artificial blood vessel A woven with wefts extending inthe circumferential direction thereof, wherein the warps are ofmono-filament made of polyester (about 15 denier) and the wefts are ofmulti-filament made of a plurality of superfine filaments (about 50denier) interwoven. The cover 7 is coated, if necessary, with waterproofmaterial, for example, collagen or albumin, to prevent leakage of blood.

The end wire rings 10₁, 10₂, whose inner diameter generally correspondsto that of the above-mentioned cover 7, are axially spaced apart andarranged face to face, and are fixed to the opposite ends of the cover 7by suturing or with adhesive as shown in FIG. 2. The circumferences ofthe end wire rings 10₁, 10₂ are covered with protective braid members10a, which are closely fixed to the end wire rings 10₁, 10₂ atappropriate positions with thread, adhesive or the like.

The intermediate wire rings 12, which comprise, as shown in FIGS. 1 and2, one or two wire rings 12a wrapped with protective film 12b made ofcloth or the like, are arranged axially equidistantly between the endwire rings 10₁ and 10₂, and fixed to the cover 7 at appropriatepositions on the circumference thereof with thread, adhesive or thelike. The above-mentioned end wire rings 10₁, 10₂ and the intermediatewire rings 12 help keep the tubular shape of the cover 7. Thorns 12a₁are formed at two diametrically opposite positions on each of those twointermediate wire rings 12 each of which comprises two wire rings 12a,so that the thorns 12a₁ may stick into a human organ so as to beembedded therein. In particular, the wires 12a of the intermediate rings12 as well as those of the end wire rings 10₁, 10₂ are made of Ti-Nialloy or the like. The wires of Ti-Ni alloy have a high resilientrestoring force, but are hard to weld. As the Ti-Ni alloy has theabove-mentioned characteristic, the thorns 12a₁ are formed by forming alength of wire 12a into a loop, whose opposite end portions are crossedso as to provide a pair of short lengths of wire projecting from thecrossing point, which is tied with a string or the like, and theprojecting end wire portions are bent to provide the thorns 12a₁ on thering. In the same manner, a pair of thorns 12a₁ are provided on anotherring formed of a length of wire 12a. The two rings are arranged side byside, with the thorns 12a₁ on one of the-rings arranged diametricallyopposite to the thorns 12a₁ on the other ring. The two rings 12a arecovered with a protective film 12b, through which the thorns 12a₁project outside.

As shown in FIG. 1, let it be assumed here that the circumference of thefront end wire ring 10₁ to the first introduced into the catheter 8 isbisected by two points which will be referred to as the dividing points41₁, 43₁, and the two midpoints between the two dividing points 41₁, 43₁will be referred to as the midpoints 42₁, 44₁. On the circumference ofthe rear end wire ring 10₂, those points whose phases are the same asthe dividing points 41₁, 43₁ and the midpoints 42₁, 44₁ will be referredto as the points 41₂, 43₂ corresponding to the dividing points 41₁, 43₁and the points 42₂, 44₂ corresponding to the midpoints 42₁, 44₁,respectively. On the circumference of the intermediate wire ring 12,those points whose phases are the same as the dividing points 41₁, 43₁and the midpoints 42₁, 44₁ will be referred to as the points 41₃, 43₃corresponding to the dividing points 41₁, 43₁ and the points 42₃, 44₃corresponding to the midpoints 42₁, 44₁, respectively. As shown in FIG.1, a pair of loops 13 of thread or the like are so formed that thecenters thereof are positioned at the dividing points 41₁, 43₁ of thefront end wire ring 10₁. Restraining strings 14 bridge the end wirerings 10₁ and 10₂ so as to prevent the artificial blood vessel A frombeing stretched unnecessarily too much along the axis thereof.

In order to implant the artificial blood vessel A of the above-mentionedconstruction into a target organ of a human body, a device B fortransporting artificial blood vessels (see FIG. 3) is used to transportthe artificial blood vessel A to the target organ of the human bodythrough the catheter 8 and a device C for introducing artificial bloodvessels (see FIG. 4) is used to introduce the artificial blood vessel Ainto the catheter 8.

The device B for transporting artificial blood vessels, as shown in FIG.3, comprises a flexible metallic tube 2 whose front end portion isconnected to a helical spring 2a for guiding, a side window 1 formedadjacent the front end of the tube 2, a pair of strings 4 having boththeir ends fixed to the tube 2 adjacent the side window 1 and theirmiddle portions formed into loops 4a, and a length of wire 3 slidablyinserted into the tube 2.

The device C for introducing artificial blood vessels, as shown in FIG.4, comprises an attachment 5 integrally connected to the catheter 8through an open end 8a thereof, and a cartridge 6 removably attached tothe attachment 5. As shown in FIGS. 4 and 5, the attachment 5 comprisesa first and a second annular member 51, 52 which are internally threadedto form female screws, a thid annular member 53 which is externallythreaded to form male screws at opposite ends, which engage theabove-mentioned female screws thereby to connect the first-and thesecond annular members 51, 52, and a straw member 54 whichliquid-tightly joins the interior of the first annular member 51 withthat of the open end 8a of the catheter 8. A check valve 55 made ofelastic membrane is provided inside the second annular member 52 toclose the open end thereof. The cartridge 6, as shown in FIG. 4 and 6,is of generally the same construction as the attachment 5 and comprisesfirst and second annular members 61, 62 which are internally threaded toprovide internal female screws, a third annular member 63 which isexternally threaded to form male screws at opposite ends, which engagethe above-mentioned female screws at opposite ends to connect the firstand second annular members 61, 62, and a straw member 64 which projectsfrom the first annular member 61 in the direction of insertion. A checkvalve 65 made of elastic membrane is provided inside the second annularmember 62 to close the open end thereof.

As shown in FIG. 4, the straw member 64 of the cartridge 6 is soconstructed that the front end portion 6a thereof is removably fittedinto the rear end portion 5a of the attachment 5 which is connectedintegrally to the open end 8a of the above-mentioned catheter 8. Inparticular, as shown in FIGS. 4, 5, and 6, the bore diameter d₁ of thestraw member 54 of the attachment 5 is a little larger than the borediameter d₂ of the straw member 64 of the cartridge 6, and the length L₂of the straw member 64 is approximately equal to the full length L₁ ofthe attachment 5. Similarly the bore diameter d₂ of the straw member 64of the cartridge 6 is approximately equal to the bore diameter d₃ of theopen end 8a of the catheter 8. When the cartridge 6 is inserted acertain length into the attachment 5, the straw member 64 is insertedinto the straw member 54 so that the bore d₂ of the straw member 54 issmoothly connected to the bore d₃ of the open end 8a of the catheter 8.The above-mentioned check valves 55, 65 are made of elastic membrane, ineach of which a normally closed hole, not shown in drawings, is formed.

A funnelled tube 18, as shown in FIG. 4, is provided as a guide tube tohelp collapse the artificial blood vessel A. The funnelled tube 18 isprovided with an inlet opening 18a of an enlarged diameter at the rearend portion, through which the tubular artificial blood vessel A isinserted into the funnelled tube 18. The funnelled tube 18 is graduallyreduced in diameter from the inlet opening 18a to end in a tubularconnector 18b of a smaller diameter at the front end portion thereof, sothat the tube 18 has a tapered inner surface 18d. The funnelled tube 18is removably connected to the cartridge by inserting the front connector18b into the rear end portion 6b of the cartridge 6. Elasticallytransformable projections 18c are provided at regular intervals from therear end portion to the front along two specific generatrices on thetapered inner surface 18d of the funnelled tube 18. When the artificialblood vessel A travels along the tapered inner surface 18d of thefunnelled tube 18, the projections 18c are elastically transformed bythe vessel A to exert a resilient counterforce to the artificial bloodvessel A thereby to contract vessel A.

In order to form the projections 18c with ease, as shown in FIG. 4,several pairs of holes 18e are formed on the tapered wall 18d of thefunnelled tube 18, and a wire 18f is inserted through one of each pairof holes 18e and drawn out through the other of the pair of holes 18e soas to form a looped projection 18c erect on the inner side of thetapered inner surface 18d, with appropriate portions of the wire 18fbeing tied with a string 18g.

The operations of collapsing the artificial blood vessel A andimplanting it into a target portion (an affected part 26) of a bloodvessel 9 by means of the device B for transporting artificial bloodvessels and the device C for introducing artificial blood vessels of theabove-mentioned constructions, will now be described below.

First, the tube 2 is inserted through the artificial blood vessel. A asshown in FIG. 7, and each of a pair of strings 4 is passed through eachloop 13 of the artificial blood vessel A as shown in FIG. 8, and thelooped portions of the strings 4 overlap as shown at 4a. Next, a wire 3has its forward end taken out of the side window 1 as shown in FIG. 9,and the overlapped portions of the looped portions 4a are hooked overthe wire 3, and then the wire 3 has its forward end inserted again intothe tube 2 through the side window 1 so as to hold the artificial bloodvessel A on the wire 3 and the tube 2 through the strings 4. Then, theartificial blood vessel A is inserted into the cartridge 6 shown in FIG.4 through the funnelled tube 18. In particular, the midpoints 42₁, 44₁are aligned with the above-mentioned generatrices of the funnelled tube18, with a common front pull string 20 being passed through the loops 13provided at the dividing points 41₁, 43₁ on the front end wire ring 10₁of the artificial blood vessel A as shown in FIG. 11. A balloon catheter23, as shown in FIG. 12, may be used, if necessary. The balloon catheter23 comprises a pipe 23a, a balloon 23b formed on the front end portionof the pipe 23a, and an opening 23c provided in the rear end of the pipe23a for air to be introduced into or taken out of the above-mentionedballoon 23b through the pipe 23a. The pipe 23a is loosely fitted overthe tube 2 of the above-mentioned device B for transporting artificialblood vessels. In other words, the rear end portion of the device B fortransporting artificial blood vessels is drawn outside from the rear endof the balloon catheter 23 while the front end portion of the device ispassed through the balloon 23b of the balloon catheter 23 and exposedoutside, with the portions of the catheter 23 through which the tube 2is passed being airtightly sealed. The rear end portion of the pipe 23ais removably connected to the tube 2 of the device B for transportingartificial blood vessels by a fixing member 24, and the balloon catheter23 and the tube 2 of the device B for transporting artificial bloodvessels can be moved together as a unit longitudinally when the fixingmember 24 is fastened, and the balloon catheter 23 can be movedlongitudinally relative to the tube 2 of the device B when the fixingmember 24 is loosened. The balloon catheter 23 is so positioned that thefront end thereof is spaced about 2 to 3 cm apart from the rear end ofthe artificial blood vessel A loosely fitted over the tube 2. Then thefixing member 24 on the balloon catheter 23 is fastened to fix thecatheter 23 to the tube 2 so that the catheter 23 and the tube 2 can bemoved together as a unit.

Before or after the above step, the funnelled tube 18 is attached to acartridge 6 as shown in FIG. 13. In attaching the funnelled tube 18 tothe cartridge 6, the connector 18b of the funnelled tube 18 is insertedinto the annular member 62 of the cartridge 6 so that the check valve 65of elastic membrane provided inside the annular member 62 is pushed openby the connector 18b of the funnelled tube 18, and the connector 18b isinserted a little into the straw 64 of the cartridge 6. The front pullstring 20 is inserted into the funnelled tube 18 through the rear endportion 18a thereof and withdrawn forward through the straw 64 at thefront end of the cartridge 6, with the tube 2 inserted a certain lengthinto the funnelled tube 18. Under the condition, the front pull string20 is pulled forward to introduce the artificial blood vessel A into thefunnelled tube 18 through the enlarged inlet opening 18a thereof.

Under the condition, as the front pull string 20 is farther pulled, thedividing points 41₁, 43₁ on the front end wire ring 10₁ of theartificial-blood vessel A are pulled by the front pull string 20, asshown in FIG. 14, and the midpoints 42₁, 44₁ are engaged by theprojections 18c provided along the generatrices on the tapered surface18d, so that the front end wire ring 10₁ is deformed with the dividingpoints 41₁, 43₁ approaching toward each other with the midpoints 42₁,44₁ serving as footholds as shown in FIG. 15. The midpoints 42₁, 44₁ arerestricted by the projections 18c and left behind the dividing points41₁, 43₁, and urged by the resilient counterforce of the projections 18cto approach each other, thereby to cause the front end wire ring 10₁ tobe folded flat as shown in FIG. 16. In short, the front end wire ring10₁ is transformed from the shape shown in FIG. 14 to the shape shown inFIG. 15, and thence to the shape shown in FIG. 16, with the dividingpoints 41₁, 43₁ where the loops 13 are provided forming forwardlydirected peaks and the midpoints 42₁, 44₁ forming the bottoms offorwardly directed valleys, so that the front end wire ring 10₁ as awhole takes a regular wavy shape. In short, as shown in FIG. 17, thefront end wire ring 10₁ is passed through the funnelled tube 18 whilebeing farther folded. Since the cover 7 is tensile, as the front pullstring 20 is pulled forward, the pulling force is transmitted throughthe cover 7 to the points 41₃, 43₃ on the intermediate rings 12corresponding to the dividing points and the points 41₂, 43₂ on the rearend wire ring 10₂ corresponding to the dividing points, as shown in FIG.18. The points 42₃, 44₃ on the intermediate rings 12 corresponding tothe midpoints and the points 42₂, 44₂ on the rear end wire ring 10₂corresponding to the midpoints are restrained by the projections 18cwhen they move along the generatrices on the tapered surface 18d, withthe points 41₃, 43₃, 41₂, 43₂ corresponding to the dividing pointsforming forwardly directed peaks and the points 42₃, 44₃, 42₂, 44₂corresponding to the midpoints forming the bottoms of forwardly directedvalleys, as shown in FIG. 19, so that the intermediate wire rings 12 andthe rear end wire ring 10₂ are also folded to take a wavy shape havingthe same phase as that of the front end wire ring 10₁. As the rings 10₁and 10₂ are folded, the braid members 10a circumferentially arrangedabout the end wire rings 10₁, 10₂ are also folded to take a wavy shape.As the artificial blood vessel A is collapsed, the thorns 12a₁ arepushed down to extend rearward or forward because of the above-mentionedconstruction.

Thus, the artificial blood vessel A inserted into the connector 18b isintroduced into the straw 64 of the cartridge 6, as shown in FIG. 20, bypulling the front pull string 20 farther forwardly. Under the condition,the front pull string 20 is untied and pulled at its end so as to bewithdrawn from the loops 13, and the funnelled tube 18 is withdrawn fromthe cartridge 6 through the rear end portion 6b thereof. Consequently,the artificial blood vessel A is contained in the straw 64 of thecartridge 6, as shown in FIG. 21, and only the pipe 23a of the ballooncatheter 23 through which the tube 2 is passed is exposed outsidethrough the rear end portion 6b of the cartridge 6 with the check valve65 opened a little.

On the other hand, the catheter 8 has been previously inserted through,for example, the coxal artery adjacent the groin F into the blood vessel9 as far as the front end of the catheter 8 has been positioned a littlebeyond the affected portion 26 such as an aneurysm of the aorta. Theattachment 5 connected to the open end 8a of the catheter 8 is, as shownin FIG. 22, exposed outside the body. Next, the cartridge 6 into whichthe artificial blood vessel A has been inserted is pushed into theattachment 5 through the rear end portion 5a thereof with the checkvalve 5 opened, and the straw 64 of the cartridge 6 is positioned sothat the front end 6a thereof is smoothly connected to the inner surfaceof the open end 8a of the catheter 8. Under the condition, the pipe 23aof the balloon catheter 23 is gripped and the balloon catheter 23 ispushed so as to be inserted gradually deeply into the catheter 8. As thetube 2 is connected to the balloon catheter 23 through the fixing member24 and the artificial blood vessel A is held by the tube 2, movement ofthe balloon catheter 23 causes the artificial blood vessel A to betransported gradually to the deep position in the body. The ballooncatheter 23 is pushed until the front end of the tube 2 is positioned atthe front end of the catheter 8, as shown in FIG. 23. At this time theartificial blood vessel A is positioned at the affected portion 26 asthe target position. Then, as the catheter 8 is withdrawn as shown inFIG. 24, with the balloon catheter 23 and the tube 2 into which the wire3 is inserted left at the objective position, the collapsed artificialblood vessel A in the catheter 8 is released at the affected portion 26in the blood vessel 9 while expanding gradually from the front end asshown in FIGS. 24, 25 and 26. The released artificial blood vessel A isrestored to its original tubular shape and urged against the inner wallof the blood vessel 9. Then the fixing member 24 shown in FIG. 12 isloosened to disconnect the balloon catheter 23 from the tube 2, and theballoon catheter 23 is advanced along the tube 2 into the artificialblood vessel A with the tube 2 kept at the objective position as far asthe front end of the balloon catheter 23 reaches the front end of theartificial blood vessel A as shown in FIG. 27, whereupon the balloon 23bis inflated by introducing air through the opening 23c as shown bydash-and-dot lines in FIG. 27 thereby to restore the artificial bloodvessel A completely to its original shape and securely fix it onto theinner wall of the blood vessel. At this time the thorns stick into theinner wall of the blood vessel 9 and are embedded therein. After theartificial blood vessel A has been thus fixed, the balloon 23b of theballoon catheter 23 is deflated by drawing air through the opening 23cand the balloon catheter 23 is pulled out from the artificial bloodvessel A by pulling the pipe 23a rearwardly. Then it is confirmed thatthe artificial blood vessel A has been fixed onto the inner wall of theblood vessel 9, and then the wire 3 is pulled out of the tube 2. As thefront end of the wire 3 passes the rear edge of the side window 1 of thetube 2 as shown in FIG. 8, the loop portion 4a of the string 4 that hasbeen caught by the wire 3 at the side window 1 is released from the wire3. Under the condition, when the tube 2 is pulled out, the string 4slips out of the loops 13 of the artificial blood vessel A. The ballooncatheter 23 and the tube 2 are then connected again by the fastener 24and pulled out of the human body with only the artificial blood vessel Aleft at the desired position in the blood vessel 9.

As mentioned above, in accordance with the invention, the artificialblood vessel A is implanted into the affected portion 26, and restoredto its original shape thereby to effectively prevent Occlusion of theaffected portion 26 in the blood vessel 9. With the above-mentionedcollapsing method, the artificial blood vessel A can be collapsed withease and accuracy. It is difficult to fold the front end wire ring 10₁into such a small shape that can be contained in a catheter 8 merely byapplying non-directional external forces thereto. However, the dividingpoints 41₁, 43₁ which equally divide the circumference of the front wirering 10₁ are pulled forward and the midpoints 42₁, 44₁ between thedividing points 41₁, 43₁ are restrained from moving forward followingthe dividing points 41₁, 43₁ by a tapered surface 18d, so that thedividing points 41₁, 43₁ form forwardly directed peaks and the midpoints42₁, 44₁ form the bottoms of forwardly directed valleys with themidpoints 42₁, 44₁ serving as footholds, so that the front end wirering. 10₁ as a whole takes a regular wavy shape. After the front endwire ring 10₁ has been folded, as the dividing points 41₁, 43₁ providedon the front end wire ring 10₁ are farther pulled forward by the frontpull string 20, the pulling force is transmitted to the points 41₃, 43₃on the intermediate rings 12 corresponding to the dividing points andthe points 41₂, 43₂ on the rear end wire ring 10₂ corresponding to thedividing points through the tensile cover 7, and at the same time thepoints 42₃, 44₃ on the intermediate rings 12 corresponding to themidpoints and the points 42₂, 44₂ on the rear end wire ring 10₂corresponding to the midpoints are restrained by the tapered surface18d, so that the intermediate wire rings 12 and the rear end wire ring10₂ are also folded to take a wavy shape having the same phase as thatof the front end wire ring 10₁, thereby to enable the artificial bloodvessel A to be collapsed into a small size with ease.

What should especially be referred to is that the method of collapsingthe appliance to be implanted in accordance with the invention ischaracterized by that the end wire rings 10₁, 10₂ provided at theopposite ends of the artificial blood vessel A are connected by only atubular cover 7 which is made of a flexible and tensile sheet; and thatthe front end wire ring 10₁ is pulled forward by means of the device Bfor transporting artificial blood vessels. The conventional method, inwhich the appliance to be implanted is pushed at the rear end-so as tobe inserted into a human organ, requires a relatively strong framemainly of connecting wire rings in order to transmit the force appliedto the rear end portion of the appliance to the forward portion thereof.However, the invention is based on the idea of pulling the front endwire ring 10₁ forward, thereby to make insertion of the appliance easyeven though no frame is provided. In addition, the cover 7 istransformed into any desired shape as the wire rings 10₁, 12, 10₂ arefolded, thereby to avoid the mutual interference of the cover 7 and thewire rings 10₁, 12, 10₂ which would otherwise occur if frames areprovided. Therefore, the method of collapsing the appliance inaccordance with this invention makes it possible to collapse the wholeartificial blood vessel A into a small size with ease by folding each ofthe wire rings 10₁, 12, 10₂, into a wavy shape.

In this embodiment, in order to collapse the appliance, the loops 13 areformed at the dividing points 41₁, 43₁ of the front end wire ring 10₁and the front pull string 20 is passed through the loops 13 and pulledforward, thereby to make the operation of collapsing the appliance veryeasy. In particular, the pulling force can effectively be transformed toa collapsing force because the dividing points 41₁, 43₁ are gathered toapproach each other by pulling the common front pull string 20 passedthrough the pair of loops 13, 13.

In this embodiment, the funnelled tube 18 whose inner surface isgradually reduced in diameter toward the front end thereof is used tocollapse the artificial blood vessel A. As the artificial blood vessel Ais inserted into the funnelled tube 18 deeper, the dividing points 41₁,43₁ and the midpoints 42₁, 44₁ are gathered to approach each other,thereby to enable the artificial blood vessel A as a whole to becollapsed into a small size. In this embodiment, as resilientlydeformable projections 18c are formed on the tapered inner surface 18dof the funnelled tube 18 so as to engage with the midpoints 42₁, 44₁,the midpoints 42₁, 44₁ are pushed to approach each other by thecounterforce of the projections 13c. A space is formed between the frontend wire ring 10₁ and the funnelled tube 18 due to the projections 18c,thereby effectively to prevent the artificial blood vessel A from beingsecurely caught in the funnelled tube 18 due to the sliding resistancewhich would otherwise be increased if the front end wire ring 10₁ werein tight contact with the funnelled tube 18. The same is true with theintermediate wire rings 12 and the rear end wire ring 10₂.

In this embodiment, the flexible braid members 10a are circumferentiallyarranged on the end wire rings 10₁, 10₂ so as to prevent particularlythe front end wire ring 10₁ from being damaged to cause the artificialblood vessel A to lose its function. In particular, if the front endwire ring 10₁ is bent beyond its elastic limit, not only it becomesdifficult for the ring to be restored to its original annular shape butalso it becomes impossible to move the ring in the catheter 8 becausethe bent portion is caught in the catheter 8. However, as the braidmembers 10a are provided, they diffuse the tension which would otherwisebe locally applied to the dividing points 41₁, 43₁ when the dividingpoints 41₁, 43₁ are strongly pulled, thereby to prevent the dividingpoints from being bent beyond the elastic limit of the ring 10₁.Consequently, the braid members 10a prevent plastic deformation of thefront end wire ring 10₁, provide the ring with a proper capability ofrestoring to the annular shape and of traveling smoothly in a catheter,and enable the front end wire ring 10₁ to be folded into a regular wavyform.

The artificial blood vessel A constructed without a frame as mentionedabove properly functions for the intended purpose. The artificial bloodvessel A in accordance with the invention is so constructed that thecover 7 itself is made of a tensile material and is held by theintermediate wire rings 12 at appropriate points thereof, and that whenthe whole artificial blood vessel A is released from the state of beingcollapsed and each of the wire rings 10₁, 10₂, 12 is resilientlyrestored to the annular shape, the cover 7 is restored to the originalproper tubular shape by the wire rings 10₁, 10₂, 12. The conventionalappliance having a frame, if put in a bent portion of a human organ, islikely to be deformed flatly because of mutual interference of thecomponent parts. However, the artificial blood vessel A having no framein this embodiment can be transformed into any desired shape so as toconform to different shapes of human organs.

In this case, as the cover 7 is of a sheet woven with warps and wefts,and the warps are made of mono-filament of polyester (about 15 denier),whose stiffness helps keep the shape of the cover 7, and the wefts areof multi-filament of polyester (about 50 denier), whose closeness givesthe sheet waterproofness, the whole cover 7 is flexible, resistive toaxial tension, keeps its tubular shape by itself, and can preventleakage of blood.

As the sheet of the cover 7 is in the form of bellows, the wholeartificial blood vessel A is easily bendable so that the condition ofthe artificial blood vessel A implanted into a human organ is improved.As the restraining strings 14 bridge the end wire rings 10₁, 10₂, thebellows can be prevented from stretching beyond the limit to becomeflat.

In this embodiment, as the flexible braid members 10a arecircumferentially arranged on the end wire rings 10₁, 10₂ of theartificial blood vessel A, the inner wall of a human organ can beprevented from being damaged by direct contact with the end wire rings10₁, 10₂ in addition to the advantage that the front end wire ring 10₁can be prevented from being plastically deformed when folded into asmall size as mentioned above. The braid members 10a also help seal bothends of the implanted artificial blood vessel A tightly to the innerwall of a human body, thereby to effectively prevent leakage of bloodthrough the ends of the artificial blood vessel A when implanted.

As the thorns 12a₁ project from the intermediate wire rings 12, theystick into the inner wall of a human organ to be embedded therein sothat the whole artificial blood vessel A is fixed to the human organ.Therefore, after the artificial blood vessel A has been implanted in thehuman organ, the thorns 12a₁ effectively prevent displacement of theartificial blood vessel A, which may cause the vessel A to be carried byblood flow downstream in the blood vessel. As each of the thorns 12a₁ isformed by curving a wire into a loop, crossing both end portions of thewire, and fixing the crossed parts with a string or the like, the thorns12a₁ can be formed with ease and remain reliable in use for a long time,even though the intermediate wire rings 12 are made of a material whichis difficult to weld.

On the other hand, by using the device C for introducing artificialblood vessels in accordance with the invention, the artificial bloodvessel A can be smoothly introduced into the catheter 8. In particular,the artificial blood vessel A is inserted into the cartridge 6 byopening the check valve 55 as far as the artificial blood vessel Areaches a position so that it is completely contained therein. Before orafter the above insertion, the cartridge 6 is attached to the attachment5 provided at the open end 8a of the catheter 8, and then the artificialblood vessel A is pulled forward farther so as to be introduced into thecatheter 8 through the attachment 5. In this case, when the check valve55 in the attachment 5 is opened, the check valve 65 of the cartridge 6is closed, so that blood flowing into the cartridge 6 is prevented fromflowing outside the body through the cartridge 6 without fail. Inaddition, if the artificial blood vessel A is inserted directly into thecatheter 8, the artificial blood vessel A cannot be inserted smoothlybecause the catheter 8 and the artificial blood vessel A are flexible,and the catheter 8 is likely to be bent by the force applied to thecatheter 8 or the artificial blood vessel A, thereby to block the pathof the artificial blood vessel A or to damage the catheter 8 itself.However, in this embodiment, as the artificial blood vessel A is to beinserted into the catheter 8 through the attachment 5 and the cartridge6, the attachment 5 and the cartridge 6 are made relatively strong andeasy to handle, so that the catheter 8 will not be broken, thereby toenable the artificial blood vessel A to be introduced into the catheter8 smoothly with ease. In this case, as the bore diameter d₁ of theattachment 5 of the catheter 8 is made bigger than the bore diameter d₃of the open end 8a of the catheter 8 and the bore diameter d₂ of thefront end portion of the cartridge 6 is smoothly connected to the borediameter d₃ of the open end 8a of the catheter 8 when the cartridge 6 isattached to the-attachment 5, the artificial blood vessel A can beprevented from being swollen in the attachment 5 and caught therein, sothat the artificial blood vessel A can be introduced directly deeperinto the catheter 8.

The invention is not limited to the above-mentioned embodiments. Forexample, in the above embodiment, the front end wire ring 10₁ has itscircumference divided into two equal arcs to set two dividing points41₁, 43₁ and the two midpoints 42₁, 44₁. As shown in FIG. 28, fourdividing points 141₁, 143₁, 145₁, 147₁ and four midpoints 142₁, 144₁,146₁, 148₁ may be set by quadrisecting a front end wire ring 110₁. Asshown in FIG. 29, three dividing points 241₁, 243₁, 245₁ and threemidpoints 242₁, 244₁, 246₁ may be set by trisecting a front end wirering 210₁.

In the above embodiment, the device B for transporting artificial bloodvessels is provided with a pair of strings 4 with loop portions 4a. Thestrings 4 need not always be provided in a pair. However, the stringsprovided in a pair are effective because a balanced pulling force can beapplied to the artificial blood vessel A. The loop portions 4a may betwisted as a whole.

As the balloon catheter 23 is used in the above embodiment, the device Bfor transporting artificial blood vessels is incorporated into theballoon catheter 23. If the balloon catheter 23 is unnecessary, theartificial blood vessel A may be introduced into or taken out of thecatheter by directly operating the tube 2 of the device B fortransporting artificial blood vessels.

The following method of supporting restoration of the appliance to beimplanted is effectively used in the above embodiment. The method is toenable the artificial blood vessel A as the appliance to be implanted tobe pulled rearward at the rear end wire ring 10₂ through the rear loops13a formed on the rear end wire ring 10₂ of the artificial blood vesselA at the points 42₂, 44₂ corresponding to the midpoints as shown in FIG.30. In particular, in the above embodiment, for example, the artificialblood vessel A may be mistakenly released at a position off the affectedportion 26 shown in FIG. 26. In such a case, when the artificial bloodvessel A is pulled backward by operating the device B for transportingartificial blood vessels, the front end wire ring 10₁ only moves towardthe rear end wire ring 10₂, so that the artificial blood vessel Ashrinks in the axial direction thereof and may not be restored to aproper shape. In case the balloon catheter 23 is inserted into theartificial blood vessel A which has been released at a constricted part,the balloon catheter 23 may not be inserted with accuracy into theopening of the rear end wire ring 10₂ of the artificial blood vessel Abut be caught by the peripheral edge of the opening, and the rear endwire ring 10₂ is pushed toward the front end wire ring 10₁ and shrinksin the axial direction thereof, so that the artificial blood vessel Amay not be restored to a proper shape. Once this happens, theabove-mentioned device B for transporting artificial blood vessels canno longer be an effective means for correcting the shrinkage of theartificial blood vessel A or pulling it back to where it should havebeen end wire ring forward.

In such a case, it is effective to use both a method of and a device forpulling the artificial blood vessel A back to the proper position afterit has been released.

FIGS. 30 and 31 show a device D for helping restoration for the abovepurpose, which comprises a pair of tubes 102 each of which is providedwith a side window 101 near its front end, and a pair of wires 103 eachof which is inserted into one of the tubes 102. Rear loops 13a areformed at the points 42₂, 44₂ on the rear end wire ring 10₂corresponding to the midpoints, and the rear loops 13a are directlyhooked by the wires 103 which have been pulled out of the tubes 102through the side window 101, and the rear loops 13a are held by thewires 103 by inserting the wires 103 into the tubes 102 again. Then thetubes 102 each of which contains the wire 103 are introduced into thecatheter 8 together with the artificial blood vessel A. In particular, abore 23d oblong in transverse section is formed in the wall of the pipe23a of the balloon catheter 23 used in the above embodiment to extendalong the length of the pipe from the rear end thereof to near theballoon 23b as shown in FIG. 32. An open window 23d₁ is formed at therear end of the bore 23d, into which a pair of tubes 102 are introducedthrough the window 23d₁ and drawn out through an open window 23d₂ formedat the forward end of the bore 23d. The tubes 102 can be moved togetherwith the balloon catheter 23 longitudinally when the balloon catheter 23is pulled forward, and they can also be move relative to the ballooncatheter 23 longitudinally when the tubes 102 alone are operated. Thedevice D for helping restoration is used when the position of theartificial blood vessel A is to be adjusted after it has been releasedas shown in FIG. 26, or when the balloon catheter 23 is inserted intothe artificial blood vessel A as shown in FIGS. 26 and 27. When theartificial blood vessel A has been released at a position a little aheadof the affected portion 26 as shown in FIG. 26, the tubes 102 containingthe wire 103 is pulled rearward to pull back the rear end wire ring 10₂thereby to cause the front end wire ring 10₁ to follow the rear end wirering 10₂. When the balloon catheter 23 is inserted as shown in FIGS. 26and 27, the tubes 102 containing the wires 103 are pulled back to holdthe rear end wire ring 10₂ not to move forward, and the balloon catheter23 is pushed into the artificial blood vessel A. Then, only the wires103 which are contained in the tubes 102 are pulled rearward as far asthe front end of the wires 103 reaches the side window 101 of the tubes102, whereupon the rear loops 13a of the artificial blood vessel A arereleased from the wires 103, so that the artificial blood vessel A isdetached from the device D for helping restoration. As a result, thedevice D for helping restoration as well as the balloon catheter 23 canbe withdrawn with only the artificial blood vessel A left in theaffected portion 26.

By using these devices jointly, a proper distance between the front endwire ring 10₁ and the rear end wire ring 10₂ can always be maintained.Therefore, it is possible to prevent the artificial blood vessel A frombeing shrunk longitudinally to deform its proper shape, and to completeinsertion of the balloon catheter 23 and adjustment of the position ofthe artificial blood vessel A quickly and accurately.

The device for helping restoration of the appliance to be implanted canbe of a construction shown in FIG. 33. The device is provided near theside window 101 of the tube 102 with a pair of strings 104 each of whichhas its front end portion formed into a loop. The loop portion of eachstring 104 is passed through a pair of rear loops 13a and hooked by thewire 103 like the device B for transporting artificial blood vessels.The tube 102 also is contained in the pipe 24a of the balloon catheter23 and transported like the above-mentioned tube 102.

In the above-mentioned embodiments, in some cases the balloon catheter23 are not used. In such cases the tube 102 is to be detachablyconnected with the device for transporting the artificial blood vesselso that the tube and the device can be transported as a unit.

POSSIBLE APPLICATIONS IN INDUSTRY

As mentioned above, the method of collapsing the appliance to beimplanted in accordance with the invention is useful to fold the wirerings, which are components of the appliance, into small, regular wavyshapes of the same phase, thereby to collapse the appliance into a smallsize. The appliance to be implanted in accordance with the invention canbe implanted into a target position without fail and has an appropriateconstruction so as not to hinder the operation of collapsing. The devicefor introducing the appliance to be implanted into the catheter isuseful to introduce the appliance into the catheter without bleeding.

I claim:
 1. A method of collapsing an implantable appliance, saidappliance including a pair of discrete end wire rings, said end wirerings being interconnected only by a tubular cover made of flexible,tensile sheet and a plurality of intermediate wire rings spaced apartfrom each other between said end wire rings and circumferentially fixedto said cover, said end wire rings and intermediate wire rings being onthe outside of said cover comprising the steps of; pulling said frontend wire ring forward against a tapered surface at a plurality ofdividing points which equally divide the circumference of said frontring while said tapered surface restrains midpoints between adjacentdividing points from moving forward following the movement of thedividing points so as to fold said front end wire ring into a wavy shapewith the dividing points forming forwardly directed peaks and themidpoints forming the bottoms of forwardly directed valleys; and pullingsaid dividing points of the front wire ring farther forward so as tofold said intermediate wire rings and the rear end wire ring into a wavyshape having the same phase as that of the front end wire ring by theeffect of restraint with the tapered surface.
 2. The method ofcollapsing the implantable appliance as described in claim 1 wherein atthe dividing points on the front end wire ring, loops are formed and afront pull string passed therethrough.
 3. The method of collapsing theimplantable appliance as described in claim 2 wherein a common frontpull string is passed through the plurality of loops and pulled togather said dividing points on the front end wire ring toward eachother.
 4. The method of collapsing the implantable appliance asdescribed in claim 1 wherein a guide robe whose inner surface is taperedwith its diameter decreasing toward the front end thereof is provided,said appliance to be implanted is introduced into the guide tube and thedividing points on the front end wire ring are pulled forward to gathersaid dividing points and said midpoints on each of the wire rings towardeach other respectively.
 5. The method of collapsing the implantableappliance as described in claim 4 wherein resiliently transformableprojections are formed on the tapered surface of said guide tube; andthe forward movement of the midpoints on each of the wire ringsfollowing the front end wire ring are restrained by contact with theprojections so that the midpoints are urged toward each other.
 6. Themethod of collapsing the implantable appliance as described in claim 1wherein said end wire rings are circumferentially covered withprotective material.
 7. The method of collapsing the implantableappliance as described in claim 1 wherein said tapered surface isconical.